More things to VR trainer. I spent time with some people and it looks that we will likely proceed with bringing VR trainer to market. The main criteria for design are high quality, very competitive price, small size and range of mechanical and other parameters that should satisfy pros.

We intend to use electric motors for resistance unit since they allow realistic of simulation of uphill, downhill and coasting if motor control is properly implemented. The trainer will also have true power-meter (yes it looks like we've found cheap and good quality solution for that) so it could be used to realistically compare results while doing online/network races workouts, provide spin-scan analysis etc, etc.

Now I have a question for you people.

I have tried few trainers, including Tacx Fortius VR trainer which I own. They all have problem of tire slippage when emulating tough hills. So I plugged bunch of number and formulas into Excel spreadsheet and quickly discovered that combination of human and bicycle can generate insane amounts of torque when staying in low gears. Existing trainers use small diameter shaft and therefore have really small contact area between the shaft and and bicycle tire. Combination of high torque / small shaft diameter leads to tire slippage then

It is not that difficult to increase that contact area by using larger diameter shaft but then there are no existing motors on the market with acceptable combination of price, weight, power and torque.

So one of the potential solutions is electronic gearing. If cyclist uses toll gears on his/her bike then the amount of force generated at shaft - tire contact area is well within a reasonable bounds. It will be possible then to simulate up-shifts and down-shifts by using motor controllers. We can even add some little jerkiness and proper sounds at shift moment for fun and realistic effect. You would not have to tell the controlling software what real gear you are using since combination of bike / motor would have enough sensors to figure that out.

So the advantages of using this approach are:

1. Significant lowering of cost.
2. No tire slippage.
3. Low wear on training tire.
4. Ability to simulate various chainring / cog combinations without really buying and installing all those. For example you can upload elevation profile of particular course to trainer and then "ride it" and select which combination works best for you on that particular course.

The disadvantages are:

1. You would not be using your brifters but small buttons that could be placed on the handlebar in position of your liking.
2. Since you only be using few real gears on your bike it'll probably lead to excessive wear of those most used cogs but that is probably what happens in real life anyways.